Switching power converters are widely used as power supplies due to their relatively high efficiency and small size. For example, information technology devices, such as computing and telecommunication devices, generally include one or more DC-to-DC switching power converters to provide local power to one or more device components, such as to provide power to device processors or to device memory.
A switching power converter typically includes a switching circuit, an inductor, and a controller. The controller controls the switching circuit to repeatedly switch a voltage across the inductor between at least two different levels, thereby causing current through the inductor to repeatedly ramp up and down, resulting in power transfer between the converter's input and output ports. In many instances, the controller controls switching circuit operation to regulate one or more converter parameters, such as input or output voltage, input or output current, and/or input or output power.
Switching power converters were historically formed of a number of discrete components. Advances in integrated circuit technology, though, have enabled integration of numerous components in a single package, thereby reducing the number of discrete components required to form a switching power converter. Such component reduction helps reduce switching power converter size and also promotes converter performance by minimizing impedance and signaling delays associated with discrete component interconnections. Additionally, minimizing the number of discrete components through integration also typically promotes reliability, manufacturing simplicity, and low cost.
However, many conventional switching power integrated circuits do not include an inductor, due to the difficulty of incorporating magnetic devices in integrated circuits, using conventional technology. These integrated circuits must be coupled to a discrete inductor, thereby preventing complete converter integration.
On the other hand, conventional integrated circuits including inductors typically compromise on inductor performance, integrated circuit package size, and/or manufacturing complexity. For example, some conventional switching power converter integrated circuits include an inductor with a small magnetic core, or even no magnetic core at all, to achieve a desired package size. A small core (or no core), however, may prevent the inductor from achieving a sufficiently large inductance value, thereby impairing converter performance. Furthermore, a small magnetic core is often prone to magnetic saturation at high current levels, thereby limiting inductor current capability.
As another example, U.S. Pat. No. 7,688,172 to Lotfi et al. discloses a power module including a single winding inductor and a semiconductor die. The inductor's winding is formed, though, from several discrete components that must be joined during the module's manufacture. Thus, Lotfi's inductor is relatively complex to manufacture. Additionally, Lofti's discrete winding components are prone to electrically shorting to external components. Furthermore, the magnetic flux path in Lofti's inductor is poorly controlled, potentially causing electromagnetic interference and/or undesired heating of external components.